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HISTAMINE

HISTAMINE. Storage Sites. RELEASE. Rlease. Primary mechanism during allergic reactions IgE antibody interacts with antigen on the surface of mast cells Enzymes as trypsin or drugs as morphine liberate histamine without prior sensitization Inhibition of release with β 2 agonists.

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HISTAMINE

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  1. HISTAMINE

  2. Storage Sites

  3. RELEASE

  4. Rlease • Primary mechanism during allergic reactions IgE antibody interacts with antigen on the surface of mast cells • Enzymes as trypsin or drugs as morphine liberate histamine without prior sensitization • Inhibition of release with β2 agonists

  5. SYNTHESIS & INACTIVATIONTION

  6. Mediator Histamine Neurotransmitter CNS ANS H 1 + H 2 + H 1 H 3 + H 3 -ve presynaptic autoregulation

  7. Histamine receptors

  8. Histamine receptors antagonists

  9. Diphenhydramin ( First generation) H1 antagonists • Clinical uses : • Insomnia • Motion sickness

  10. Loratadine (Second generation) H1 antagonists • Non-sedating • Clinical uses • Allergic conditions : • allergic rhinitis • Conjunctivitis • Urticaria

  11. Cimetidine H2 antagonists • Inhibitor of gastric acid secretion • Used in the treatment of : • peptic ulcers

  12. BETAHISTINE H3 antagonists • Used in treatment of : • vertigo in middle ear

  13. Eicosanoids

  14. INHIBITORS OF EICOSANOIDS

  15. Drugs Phospholipids Corticosteroids Phospholipase A2 Arachidonic Acid Zileuton NSAIDs Lipoxygenase COX1 & COX2 Prostaglandins PGE2, PGD2, PGF2 Leukotrienes LTA4, B4, D4, C4 Prostacyclin (PGI2) Thromboxane (TXA2)

  16. ACTIONS

  17. Vascular smooth muscles: PGE2 and PGI2 Thromboxane A2 Potent vasoconstrictor. Potent vasodilators .

  18. Blood: TXA2 a potent inducer of platelet aggregation. PGE2 and PGI2 inhibit platelet aggregation

  19. Inflammation: One of the chemical mediators in inflammatory reactions.

  20. Bronchial smooth muscle: -PGE2 cause dilatation. -PGF2 -LTs and thromboxane are potent bronchoconstrictors in man → allergic bronchospasm.

  21. Uterine smooth muscle: PGE2 and PGF2→ Menstruation/ Dysmenorrhea/ Labor contractions

  22. GIT smooth muscle: - PGE2and PGF2 and LTs • GIT • motility

  23. GIT secretions: PGE2 , PGE1PGI2 ↓acidand pepsinogen secretion . mucin, water and bicarbonate & Blood flow.

  24. Kideny PGE2 and PGI2 increase renal blood flow and diuresis.

  25. Central and peripheral nervous systems • Fever: PGE1 and PGE2 increase body temperature.

  26. CLINICAL USES OF PGs ANALOGS

  27. Carboprost • PGF2α ( analog) • Abortifacient: • Trigger abortion in first trimester.

  28. 2) For postpartum haemorrhage • vasoconstriction + uterine muscle contraction

  29. Latanoprost (PGF2α analog ) eye drops in open angle glaucoma. ↓ IOP by enhancing outflow of the aqueous humar.

  30. Alprostadil (PGE1analog) 1- Injected in corpus cavernosum of the penis for some forms of male impotence.

  31. 2- In congenital heart anomalies to keep the patent ductus arteriosus until surgery.

  32. Misoprostol • (PGE1 analog) Peptic ulcer

  33. Thank you

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